Testing equipment for automatic telephone systems



Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10, 1925 PIfECTOE 4 65456701? E i P T lllllllllllllllllll M m M W Sp Jr v w w 7% 9 7 ET n M M 4 K m 4 4 Wm H N, s F 7 a D Haw H mm 50 J. 2o o o o o r@ o o o o l/o jw/o f/o/f -Inusn or l fl'ar'hn L. Nelson Feb.21, 1928.

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E H?!" L.Ne'lsun fi m Filed Aug. 10. 1925 4 Feb. 21,1928. 1,659,832

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10 1925 10 Sheets-Sheet 3 TEST SEA/DER fol 10.9

Filed Aug. 10. 1925 M L NELSON TESTING EQUIPMENT FORAUTOMATIC TELEPHONESYSTEMS Feb. 21, 1928.

Im.rsn CIT-- l L arZm L. NEZsun fimdfl Feb. 21, 1928.

L. NELSON TES TING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug.10. 1925 10 Sheets-Sheet 5 N M Q QQMRZOU MMQENW hWMh Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10. 1925 10 Sheets-Sheet 6 Inusn UI- Hm L. Nslsun Feb. 21,-1928.

" M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10. 1925 10 Sheets-Sheqt -Inusn m: Mar 111 L.Na1sun N 3 MR his NQQFeb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10. 1925 10 Sheets- Sheet 8 I: Jun- M. L. NELSON TESTING EQUIPMENTFOR AUTOMATIC TELEPHONE SYSTEMS Feb. 21, 1928.

H a M M M knwR Feb. 21, 1928.

M. L. NELSON TESTING EQUIPMENT FOR AUTOMATIC TELEPHONE SYSTEMS FiledAug. 10. 1925 10 Sheets-Sheet. 1o

M b H M M a M Q I ance will be accurate and reliable.

Patented Feb. 21, 1928.

entree STATES v 1,659,832 PATENT OFFICE.

MARTIN L. nntsoinor :PARKRIDGE, ILLINOIS, ASSIGNOR, BY MESNEASSIGNMENTS,

T0 AUTOMATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA-V WARE.

TESTING EQUIPMENT FOR AUTOIVIATIC TELEPHONE SYSTEMS.

Application filed August 10, 1925. Serial No. 49,226.

of directors and which intercepts the digits that the director sends outand records them as received properly or improperly.

In the so called director system, a relatively small number ofdirectors'are em ployed in common to a group oftrunks to register,translate and retransmit thedigits of telephone numbers. As soon asthese digits have been retransmitted, the director disassociates itselffrom the trunk and can not be readily further identified with thepending call, inalrin it very difficult to determine just which directoris not functioning properly. Therefore it is imperative to good servicethat the directors be kept in first class condition so thattheir'perforn'i- The best known way of keeping such equipment inreliable order is by routining it, that is, by frequently applyingcharacteristic tests, which, if properly executed indicate that theequipment is functioning properly. The director has many functions toperform, and

in order to definitely determine that the mechanism is performing allthe functions properly, a large number of separate tests must beincluded in the routine. If these tests are applied manually, aconsiderable period of time is required for each director and themaintenance costs are therefore made unduly high.

Accordingly, the principal object of this invention is the provision ofa director routine test mechanism which will automatically routine agroup of directors without attend? ance, other than that required tostart-the mechanism and to record and repair the faults found. I

A further object is to provide a testing mechanism which seizes eachdirector in its consecutive order, applies a test to it and if the testis properly completed, releases that director to common usage and seizesthe next,

' on which the same test is applied.

Another object of this invention is to provide a testing mechanismwhich, is arranged to camp on a busy director, if that director isengaged in setting a call, and to skip a busy director, if that directoris made per-' manently busy by means of the director busy key providedfor the purpose.

A still further object of this invention is to provide-attestingmechanism arranged to apply a large number of tests to each director,and still further arranged. so that it changesfrom one test to anotherafter the Y former test has been applied to all of the directors in thegroup. i

A still further object of this invention is to provide a testingmechanism which, when a fault is found will indicate which directordefaulted, and the exact nature of the fault,

and which will hold the director and test mechanism in place While asignal is sounded to summon the attendant to the mechanism to locate andrepair the fault.

' A further object of this invention is to provide a test mechanismwhich will exercise a director, that is, repeat the same test on anydirector indefinitely, to make sure.

that that mechanism functions properly.

A still further object of this invention is to provide atest mechanism,which willroutine a single director, that is, run all of the routinetests on a director to inake sure that that mechanism is functioningproperly.

Further objects of this invention whicl are not specifically enumeratedhere will be description and apparent from the detailed claims whichfollow.

The drawingsrcomp'rising Figs. 1 to 10, inclusive, when arranged asshown in Fig. 11, show suflicient details to enable a clearunderstanding of the construction and operation of my invention.

Figure '1 shows a director mechanism together with the trunk circuitwhich renders it available to the director selector and to the testmechanism.

Figure 2 shows the test director selector, which connects with thedirectors to be tested and controls the application of tests thereto.

Figure 3 shows the test sender mechanism by which a certain number issent into the director to set the mechanisms therein in their proper.positions to perform the desired tests.

Figure 4 shows the test selector mechanism which determines which ottheseveraltests will be applied. to the directorthat is being tested.

Figure 5 shows the test sender control relays comprising two groups; onegroup Which controls the digits and the other group which controls theimpulses in. the digits.

Figure 6 shows the test set up relays A by means of which it isdetermined what number will be: sent into the director and what numbermust be received fro nthe;

director by tlie test mechanism, in testA,

Figure? shows the receiver control re-. layswh ch count. the impulsesreceived iromthe, director. to determine whether or; not.

the translated number. has been properly sent, by, the dir-ec iOl. showsthe, impulse lamps.numbered, conl t iv y r m .0 o 1 inclusi e, y ans. ofwhich a .i'ault. islocated,

Figure 8-.shiow-s-the receiver digit; controlrelaysby'meanso'f whichtliedigits to. be.

received are determined in cooperation with the set-up relays-of Fig. 6and alsothe digit lampsby means of which the fault is located withvrespect tothe digits. I

Figure 9 shows a. second test setup, relay group hereafter designatedtest C, which is arranged to replace Fig. 6 and to control the senderand receiver mechanism when test C is being made in a manner which willbe explained more fully hereinaafter.

FigurelO similarly istanother test set-up controhherea'iter designatedas test D, which. isarranged to replace F ig. 6 and to.,control thesender and receiver mechanisms whentest D; is-being transmitted as willbe. eX-

plained hereinafter,

Inan actual installation Lpropose to. mul-..

tiple' the digitand impulse wires from the sender control relays, shownin Fig. 5, to a;

pluralityof terminal pins on thesender TDF shown in Fig. 6, andiin a,similar manner to; multiplethe. impulse and digit wires fromthe receivercontrol relays showniin Figs. 7 and 8 to a plurality of terminal pins onthe receiver IDF shown in Fig. 6. The test setup relaysA, shown in Fig.6 are connected to one set ot terminal blocks', both in the. sender andreceiver IDFZs, illiClSlDlllLIlY the This drawing also be explained, thedrawings showing that test set-up is substituted for the former drawing,it. being'understood that this arrangement does not designate analternative test means, but is merely an arrangement to simplify thedrawings as'much as possible.

It should be noted that I have shown in Fig. 6, three sets of normallyclosed springs, 922, 102 i, 10%, that are not associated with any relay;the two latter springs also appear in Fig. 9, and the former in Fig. 10.I hayevchosen to show certain, circuitsz'in this manner in connectionwith the above mentioned plan of drawing simplification.

The springs, 922 area .set of break, springson. relay 903. of test-C.Except when testQ is being employed, these spings are closed;

to connect. the director selector step conducitor 1- to the directorselector, step conducton, 2. Similarly the springs 1024, which are inthe relay 1009 of the test 1) connect they star-ticonductor to the start1 conductors cept duringthe application ,o:t, tes t:D,., Also thepulse lconductor. and: the pulse 2 conductor are-joined together through.springsv 1015 except. when relay 10,07 isenergifzed during test D. Thesespringsthatare shown detached .lirom their relays, remain closedthroughout the application of the, test in which theyare so shown, andmay be re.-

garded as a solid connection during' the consideration that test. v

Throughout the drawing-5. .111 order to v avoidundue complications, lhave shown a plurality of batteries whereas-inreality there would be butone battery, preferably withits positive .pole grounded. v

Referring now to Fig.1 1n more detail.

I liavesl own a skeleton of a: director inechar;

nisn such asis disclosed intlull in my (10-- pendi m application Serial.No. 719,459, filed June 12, 1924. This mechanism which is common to atrunk group is accessiblethereto through the medium-oi thedirectorselector, and is. operable to register, translate and retransmit thedigitso't telephone num-. bers. Pi'ovidedwvitli each director is adirector busy key by means of which.v that directo:v canbemadepermanently busy'and,

inaccessible to the director selectors .in; the,

well known manner by'placing; ground po tential on theprivate or testingconductor.

In Fig. 2, I have shown a test director selector which is a. directorselector similar to'thc regular director selector indicated in Fig. 1 bymeans of which the testing mechanismis connected. to the directorsto'betested, VJith the director selector arranged. as shown n, Fig. 2, amannnum of 24 di-.

rectors can be made available to the test mechanism,the twenty-fifth.contact of the group being utilized for other purposes, as will beapparent hereinafter. It will be ize understood that it is by of examplethat it I have chosen this arrangement and that by the use of asecondary switch, a maximum of 576 directors can be made available tothe test mechanism.

Briefly, the operation of my invention is as follows: when the attendantstarts the test mechanism by operating certainkeys, the test directorselector steps its wipers on tothe trunk leading to the first directorof the group. If that director is engaged at the time setting up a call,the test director selector camps there, lighting a'lamp, indicating thatthe director No. 1 is busy. As soon as that director becomes idle, thetest director selectorseizes it and makes it busy to the regulardirector selector so that the test will not be interfered with.Simultaneously with the starting of the test director selector, theattendant operates the key to start the test sender impulsing relay inoperation and to step the test selector into connection with the firstbank contact, so that the testing mechanism is arranged to send out thefirst test, which is test A. The test set-up for the first test is shownin Fig. -5, the relays 601 and 602 being energized through the banks ofthe test selector of Fig. l, to connect up the sender and receivercounting relays in accordance with the digits of the first test. In thistest the testing mechanism is arranged to send in to the director thedigits 431 in response to which the director sends out the digits 3481.In sending the digits into the director the test sender impulses in thewell known manner to send ground im pulses over the impulse Wire to thedirector, the number of impulses being counted by the counting relays,which are arranged to cut off the impulsing when the proper number ofimpulses have been sent, in this case 4.. At the end of the first digit,the sender digit control relays function to connect'the impulse countingrelays so that they Wlll count out the correct number of impulses forthe second digit, in this case a 8, that digit being transmitted intothe director in the same manner as was the first digit. In a similarmanner the remaining digits are sent to the director.

I After the impulses have been transmitted into the director mechanism,it starts to send out over the loop conductors a series of digits, thenature of which is dependent upon the register mechanism setting of thedirector itself, as explained in detail in my.

above mentioned copending application.

Res onsive to the ulsin b the director p b d 7 the test set mechanismpulsing relay is oper ated to transmit impulses of ground to thereceiving counting relays, setting up a com bination of counting relaysin accordance with the number of impulses received from the director. Atthe end of the transmitting of the first digit the test set mechanismmakes a test to determine whether or not the digit received was thedigit that should be received, that test being made by projecting groundout on the fault wire which is extended through the first combination ofthe receiver impulse and digit counting relays back to the testconductor. If the digit was properly received, the digit control relaysof 8 are operated to prepare the receiving mechanism for reception ofthe second digit of the call number.

When the test setup relays 601 and 602 are energized to put the senderand receiver mechanisms of the test set under the control of test set-upA, the sender mechanism is arranged to send in to the director thedigits e 81, responsive to which the director must send out the digits3431. If, for any reason, the director sends out a. wrong digit, thetest loop mentioned previously will not be completed through thecounting relays since those relays will be improperly set, and as aresult the test director selector will lock up holding the faultydirector to prevent its seizure by a subscriber, andthe test lamps willbe lighted to indicate the nature of the fault. f, for example, thedirector sent out a first digit of 4 instead of 3, director No. 1 beingtested at the time, the test lamps would be lighted to indicate thatdirector No. 1 had defaulted and that it haddefaulted on the first digitsending out a 4; as the first digit. By reference to the test chart orany suitable record, the attendant knows that the first digit should bea 3. Inasmuch as-the test director selector is holding the faultydirector in its operated position, the attendant can examine thatdirector in detail to determine the cause of the fault. The attendant,upon finding the trouble, may repair the same, and in order to make surethat he has properly repaired the director, he will operate a so calledconsecutive test key on the test set mechanism.

Operation of the consecutive test key arranges the circuits of the testdirector selector so that the test then being applied is repeatedlyapplied to the same director, in this case director No. 1, to exercisethat director so that the attendant may make certain that it isfunctioning properly.

When the attendant is certain that the director No. leis functioningproperly he reoperates the consecutive test key, whereupon the test isrepeated on the director No. 1 once more and if the test mechanismreceives the proper combination of digits, the test director selector atthe end of the test selects out and picks up director No. 2, and if thatdirector is not busy at the time in the process of setting up a call, itimmediately receives the same test on it. At the end of that test thedirector selector steps onin search of director No. 3, which for themoment will be assumed to be made busy by means of the director busykey. In this case the t st director selector will not camp group of onthat trunk, but will advance immediately and pick up director 4, for thererson that director N0. 3 is probably made busy because ofsome faultalready known to the attendant and there would be no advantage gained intesting the director.

After the entire group of directors have been tested with the test it,explained hereinbefore, the test selector shown in Fig. 4, immediatelyafter the completion of the test on the 24th or last director of thegroup. advances its wipers one step to change the test set up relay,that is, to piclt out a new test to be applied to the group directors.In Fig. 4 l have shown the test applied to the directors when the wiper411 in the first six positions of its bank. And the Bapplied to thedirector when the wiper i1 is in the second 8 positions of its bani. thetest C applied to the dire wiper is in the third 5 positions Oil thebani with the test 1) applied only once as be obvious from the b: 1cans: have made thisparticuiar set-up ct selector merely by way of exampe as it is possible to apply 25 dill-oi each bank contact encount' it'dby the w 411. The test A shown on to. 6, is the most simple test to thedirector, exercising the mos; function of the director, in which case dits are impulsed into a greater or lr number of digits sent out by thedirector mechanism. Test B, which is selected when the wiper 411 of thetest selector reaches the second group of bank contacts, may be substantially like test A and need not be explained in detail here.

When the wiper 411 reaches the third bank-contacts, it picks out thetest C, which is shown in test set-up Fig. 9. With Fig. 9 substitutedfor Fig. 6 between Figs. 5 and 7 and to the right of Fig. 3, thedrawings are arranged to show the circuits of the test set when the testC is being made. It will be noted that the circuit is completed from thewiper 411 01" the test selector through the test control'conductor C tothe windings of the relays 901 and 902., energizing those relays toplace the sender and the receiver mechanisms test set under,

the control of the test C. This set is arranged to impulse into thedirector 111 and to receive from the director the digits 111 followed bya director cutoff. The test set up is further arranged so that the abovementioned test is repeated twice on each director before the testdirector selector steps on to pick out the next idle director. Becauseof the peculiar setting oi the director digit registers when the digits111 are recorded, there is a possibility that these registers will notrestore to normal properly when the director cuts'ofi, particularly itone of the digit registers happens to be a little register recording thethird 1 of the :called number had tailedto release properly when thedirector was called upon to call that number ,the third digit of thenumber would contain t vo. impulses nstead of one. When the digits werereceived by the test mechanism this error in thcQt-hird digit of thenumber would be recorded as an indication to the attendant that thedigit-register otth-c directorwas-slug ash to release. attendant wouldthen repair the fault and exercise the director several times to makecertain that he had properly adjusted the faulty mechanism, beforeproceeding with the test, as .set forth before. Aside vfrom this changethe test set-up C is. an exact duplicate of the test A and need .not beexplained further detail at this time.

When the wiper 411 of the test selector reaches the bank contact towhich is attached the test control conductor D, the circuit is completedto the test set-up irel-ays 1001and 1009 of Fig. 10., to bring thesender'and receiver mechanisms of the test set underthe' control of thetest D. By substituting Fig. 1.0 for Fig. (Sbetweeh Figs. 5 and 7 and tothe right of Fig. 3.,the drawingsare arranged to show the circuits ot'the test .mechanism when the test set-up D is employed. The test D isarranged to test the time limit release of the director mechanism]Inasmuch as there are but a comparatively iew directors employed in anexchange it exchange would function to seize the director in the wellknown manner, and it no impulses were received by that director. itwould not move out of normal and would become permanently out ofservice. Or, it a subscriber started to call a number and after diallingone or'two digits, he forgot the rest of the number or neglected to dialit, the director again would be tied up as sutli cientnumber ot-digitsto release it have not yet been received. To guard against contingenciesof this kind, a time limit pulse is provided which, after a definiteinterval, it no impulses are received by the director. causes thedirector to release the established train of switches and to dialagpredetermined number, which may either return a busy toneto thesubscr1ber or connect the .subscrlber to a supervising operator. Thetest D 18 arranged to determine whether or not this.

The

Inc

rector.

The director sends out a9 and then waits. At the end of an interval thetime pulse sent out by the time pulse mechanism operates both thedirector and the test-set mechanism,

causing the director to rel-ease and send back a and to light the lamp413 to notify the attendant that the routine has been completed on allof the directors and that the test is ended.

. In the testing sender, shown in Fig. 3 is an interrupting relay 301which is arranged to impulse into the director mechanism. In order thatthe test may be successfully carried on, it is'neces sary that thisrelay be maintained in standard adjustment, so that the impulsesreceived by the director mechanism will be the same as are received bythe director from the director selector when the director is beingusedto set up a call. For this purpose I have provided the jack springs 320and 321'by means of whichI can connect a testing mechanism such as shownin my copending application, Serial No. 744,- 528, filed October 18,1924. By operating the keys 322 and 323 I am able to divert the impulsesdelivered by the springs 325 of the interrupting relay into the testmechanism disclosed in the above mentioned application. This mechanismis arranged to determine the speed and impulse ratio of the impulses,and serves as a guide in the adjusting and timing of the standardinterrupting relay 301 of the test sender.

It may happen that the attendant, after repairing one of the directormechanisms,

may desire to place a particular one of the tests on the director he hasrepaired, and to repeat that test a plurality of times on that directorto limber up the mechanisms he has repaired. He may do this by startingthe test mechanism in the above manner, and

then by manually stepping the director selector to the desireddirectorby operating the director selector step key 234, and then step thetestselector to the desired test by operating the test selector stepkey.He will then operate the consecutive test key 241 to the position inwhich it exercises the di- In this manner the attendant is able to put aworking test upon the parts of the director that he has repairedorrep'laced, and by this means he is able to definitely deter minewhether or not he has put the director mechanism in its proper workingorder.

In the event that the attendant desires to place all of vtheroutinetests on the director that he has repaired, he arranges the testingmechanism to exercise the director, and in additionoperates the directorroutine key 226. The circuits are then arranged so that at the end of asuccessful test, the ground pulse that normally would operate thedirector selector'motor magnet 212 is diverted to the test selectormotor magnet 404,

energizing that magnet to advance the wipers 410-411 one step. By thisarrangement all of the tests in the routine are applied to the singledirector.

Having thus described my invention in general, I will now proceed with adetailed description of its operation as it places the various testsupon the directors. First, I shall explain the detailed functions as thetest A is appliedto the directors.

Starting me test mechanism.

In order to start the test mechanism in motion, the attendant firstoperates the interrupter start key 324, closing the circuit from groundthrough springs 324 to the winding of interrupter relay 301 and the Iwinding of relay 303 in seriesto grounded battery. The'relay 301energizes over this circuit and attracts the armature 302 to close thecontacts 302 and 326, thereby shunting out the winding of relay 301 andproviding a direct path from grounded spring 324 through springs 302 and326to the winding of relay 303. Relay 303'being marginally adjusted willnot energize in series with relay 301, but will'energize when the latterrelay is shunted out. Relay 301 being shunted out deenergizes after amoment allowing the armature spring 302 to retract to operate thesprings 325. As soon as relay 301 has removed-the short circuit fromitself, relay '303 deenergizes, closing the spring 327 for a purposewhich will be explained hereinafter. Relay 301 again attracts itsarmature 302 and, shunts itself out to energize its relay 302 anddeenerg'ize itself as before. Because of the weight on the armature 302,its movement is pendulum like and timed to vibrate at'the rate of 10 persecond so that the spring 325 and the relay 303 are both operated atthe'rate of 10 operations per second. After havingstarted'the impulsingrelay in mo tion' the attendant then operates the test step 1 key 419,closing a circuit from ground to springs 419 through the winding ofrelay 404 to grounded battery. The relay 404 en ergizes and prepares toadvance the wipers 410 to 411 one step. This switch mechanismv being ofthe well known rotary line switch type, advances its wipers when themotor magnet 404 deenergizes rather than when the magnet is energized.When the attend ant releases the key419 magnet 404 deenadvancing thewipers 410 and 411 Ii I;

contact a. p 1 ground through key 420 and its break contact, springs417, Wiper 411, noW in contact- "with bank contact .a,test controlconductor tothe firstbank contact in which position the wiper'411 is incontact with the'ban'k A- 'circuit is then closed from A, through thewindings or relays 002 and 601 In series to grounded battery. Relays"601 and'602 energize over this circuit, there- 'bypreparing the testsender and'test' receiver controlled to send out thetest A.

Test set-up A.

Relay 602 upon energizing'closes'a circuit "from ground through springs"614' and its make contact, througlrthe start 1 conductor, throughbreak-contacts 1024 through "thestart 2 conductor through t'h e'breakcontacts o1": fa'ult'release'key 261, through break contacts25.4,through the winding of relay 204 to grounded battery. Relay 204energizes over the above traced circuit and at spring 242 closes acircuit from ground through springs *242, spring 235, and its breakcontact, through the winding or relay 201, through spring 232 anditsbrcak contact through the wiper 223, now assumed to be in connectionwith the bank contact to'which private conductor 451 is connected, overconductor 451 through the winding of relay 806 or" the director togrounded battery. Relay 806 ofthe director and relay 201 01 the testdirector selector energize over/his circuit, the former to start theinterrupter relay 811 of the a director mechanism, and the latter toseize the director, and to connect it torthe test mechanism.

Sez'ein-g tlredirector.

Relay -201 upon energizing at spring 232 and its make contact putsdirect ground upon the private conductor 451 leading to the director C,and making that director busy in the banks of the director selector. Atsprings 230, 231, and

-233, the relay 201 closes a circuit connect- -'tor 449, through thewipers "221, springs 231,

through the upper winding of relay 205, to grounded battery. Relay 205energizes over the above traced circuit and at springs 244 closes acircuit from ground through spring 260 and its break contact throughspring 244 and 244,-through spring .246 and its break contact, throughthe Winding of rela'y 206 to grounded battery. .Relay 206,

upon energizing at springs '248 and 247,

ground potential on through relay 501,

closes a point in a 'circuit through the pulse Wire and release "testwire, respectively, without effect at 'thls time inasmuch as theconductors areheld open in theitest setup control. Relay 206 at spring245 closes a circuit between the start 1 conductor and the sender startconductor thereby closing a circuit from ground at spring 614 and itsmake contact over start 1 conductor through springs 245 to the senderstart conductor, through springs 332, through the winding of relay 304to grounded battery, vwith a vparallel branch leading over the hold 2conductor to the terminals o1 .relays523, 525 and527 ot the sender digitvcontrol. Relay 304 energizes over this circuit andprepares the testsender for impulsing. rupter springs 325 atthepresent timeiareshortcircuited by means o'f the springs 332,

The" inter- V a circuit being traceable from the make contact at sarim332 throu h ke ,s* rin s 323 l s s y 1. e

and its break contact, through interrupter springs 325, through-key'sprmgf322 and its brealn contact, vthrough normally closed con- ;tactscontrolled by spring 334.,to the main spring 332. V r i The tcszf'semlerimpulsingi,

Vhen the relay 303 energizes in 'themanner hereinbefore describedfit.closes a circuit from ground through the sender start conductor,normally closed contacts controlled by spring 334, through spring 327and itsbreak. contact through spring 330 and its break contact conductor340 s rin 531, through the Winding of relay 500 to grounded battery.Relay 500 energizes over the circuit and at. spring 530 locks itself tothe holding conductor 543 in series with relay 501. The relay 501doesnot energize at this time for the reason that there both ends oi itswindone being traceable from mg, ground grounded spring 331 and itsbreak Contact,

conductor 343 and the other. ground through spring 530- to the circuitjust traced for relay 500. V] hen the armature 302-01? theinterrupterrelay 301 short circuits that relay, relay 303 ei-rergizesand at spring327 opens the energizing circuit (if-relay 500 which 15 locked in serieswitl relay 501.

Relay 501 then energizes over a circuit troin ground through holdingconductor 343 through spring 530, re-' lay 500 to grounded battery.Relay 501,

upon encrgizingcat springs 532, closes a circu t from ground throughsaid springs through conductor 341, through thewinoing or relay 306 tobattery. Relay 306 energizes over the above traced circuit and at spring332 opens the previously traced circuit-for relay 304 and removes theshort circuit "from theimpulse 'spri-ngs .325 ofthe interrupter relay301. The sender mechanism is-now in position to send out the first'digitof the called number, that digit being determined by the sender IDFjumpering and controlled by the test set-up relays 601 and 602 Thesender impulses into the director.

It will be noted that the first impulse sent out by the interrupterrelay 301, atte'rthe sender ground has been received by the test sender,is absorbed in the relays 500 and 501, the secondv impulse being thefirst one that is effective to control the digit registers of thedirector. The reason for this is to make sure that the impulses sent into thedirector are standard, by absorbing the first three'impulses inrelays 500 and 501, the possibility of a short impulse is entirelyremoved. Relay 301 by short circuiting itself to allow relay 303 toenergize as has been previously explained, closes the springs 325 in theWell known manner, closing a circuit from ground on sender startconductor through key spring 322 and its breakcontact, through spring325, through spring 323 and its break contact, through the winding ofrelay 304 to grounded battery. The relay 304, which was energized over acircuit including springs 332 is held energized over the circuit justtraced, that circuit being completed before the springs 332 are opened.When the relay 301 deenergizes it breaks at springs 325 the above tracedcircuit of relay 304 allowin that relay to restore, closing the circuitwhich is traceable from grounded spring 532 over conductor 341, throughspring 328 and its break contact over the impulse conductor, throughspring 259 and its break contact, through springs 230, through the Wiper220 to the impulse conductor 452, through the Winding of relay 702' ofthe director, through the wiper 719 and the primary oflice registermotor magnet 909, to grounded battery. The relay 702 and the motormagnet 909 energize over this circuit to register the impulse in thedirector mechanism in the well known manner. When the relay 301reattracts its armature, relay 303 deenergizes closing a circuit fromgrounded sender start conductor through spring 327 and its breakcontact, through spring 330 and its break contact, conductor 340 throughspring 531 and its make contact, spring 534 and its break contact,through the Winding of relay 502 to grounded battery. Relay 502energizes over this circuit and at spring 533 prepares a locking circuitfor itself in series With the relay 503. Relay 503, however, havingground on both ends or its coil does not energize at this time. When thearmature 302 of the pulsing relay is attracted it closes springs 325,thereby closing the previously traced circuit for the relay 304, whichenergizes and opens the previously traced circuit of the relay 702 andthe motor magnet 9090f the director mechanism. The motor magnet 909falls back When its circuit is open, but the relay 702 being slow actingbecause of the copper slug on its core, remains in its-energizedposition during impulsing. .Vhen the relay 301 has again shunted itselfout, relay 303 energizes and at spring 327 opens the previously tracedcircuit of relay 502 thereby removing the ground from one terminal ofrelay 503, permitting that relay to energize over a circuitfroingrounded holdingconductor 343 through relay 503 through springs 533,through the Winding of relay 502 to battery, locking up the relays 503and 502. Relay 503' closes the springs 535, which test the first impulsepin 1 of the sender IDF to see Whether or not the first digit to bedialled is a 1. The test set-upA is arranged to transmit the digits 431,so that the first digit to be transmitted is a 4. The impulsing relayagain opens the spring 325 to send another impulse of ground to themotor magnet 909 of the director and to permit the relay 303 to againdeenergiz e to send an impulse of ground to the magnet groups 504 and505, counting 0a the second impulseof the digit.

End of first digit.

jumper 1"" on the sender IDF to the fourth impulse pi-nfthrough spring544 and make contact over conductor 342, through the Winding of relay305 to battery. Relay 305 energizes over this circuit and at spring 329closes the obvious holding circuit forthe pulsing relay 304,.whichremains energized and at spring 328 holds open the impulsing circuit tothe director thereby preventing the sending of further impulses to thatmechanism. The operation of relay 509 to close spring 544 also projectsthe ground previously traced from the spring 571 to spring 544' over apath including the digit cutoff conductor to spring 570 and through itsbreak contact, through the winding of relay on both ends of its coil inthe manner similar to the second relay of the impulse countgroup. Relay305 upon energizing locks itself to ground through spring 331 and itsmakecontact, through springs 333, through 1 relay 601, to the sender pin1", through impulse counting: relays relay 305'todgro1uided battery.Relay 305 upon energizing at spring 331 interrupts the energizesafter aninterval, removing ground from. conductor- 012 by the retraction ofsprings 3133.v Ground being removed from the digit cutoff conductor 342relay 527 is no-longer short circuited and it energizes in series withrelay 526, locking itself in energized positionito the hold-2 conductorground; vThe restoration of relay 306 re closesthe springs 332: toshortcircuit the interrupter springs 325, to maintain the relay'304eenergized after relay 305 has restored and opened springs 329. Therestoration of" relay 305 also completes at Springs 330,, the previouslytraced circuit to, relay 500,, controlled through springs 327 oftherelay 303;

' Thejnext impulse sent by the sender is absorbed, inqthe relays 500 and501 hereinbefore explained, relay 501 upon pulling'up closing a circuitto spring 532 to the wind ing of relay' 306 to remove the short circuitfrom the impulse spring 325 to allow impulses to be. sent to the/pulsingrelay 304 as previouslydescribed.

Sending the second digit.

Whenwthe relay 527: energizes, at spring 571 it removes the ground fromthe first digit wire which has been previously traced through the senderIDF to the impulse counting pin 4,. and closes circuit traceable fromground through: spring 571 and its make contact, 568 and its breakcontact, digits pin 2 through the sender IDF and spring 612, of therelay 601,. through the second digit sending pin 2 of the sender IDF andthence through the jumper to the third impulse pin, which is connectedthrough the spring 541 to the digit cutoff wire; The set-up determinesthat the second digit transmitted by the test sender is to bear 3;, In.the director, at the end of the transmitting; of the first digit,therclay 702 deenergizes after a'brief interval and close circuits bymeansof which the wiper 719 was transferred from the first bank contactto the second, thereby changing the circuit so that the secondset ofimpulses will be delivered to the secondary office register motor magnet910 rather than to the magnet- 909, The transmitting of the second digitbythe test sending equipment into the director duplicates the'processjust described 1 in connection with the first digit and need not beexplained in detail. At the end of the transmitting of, the seconddigit, the ground rector.

is supplied to the digit cutoff conductor when the springs 54,1areenergized after the third impulse, and the digit controt relays 524and 525 energize in a manner similar to that described for relays 526and 527, transferring the digit cutoff ground from the second digitconductor to the third digit conductor, supplying that ground-over theobvious circuit including spring 611 tothe first impulse spring then to,the springs 535 of the impulse counting relay 503. In the director atthe end of the second digit the relay 702 de- 7 energizes for a briefinterval and causesthe 747m" J ,h'1b'k wiper (19 to be moved to the t-ro an con 7 tact thereby completing the clrcui-t so that. the thirddigit received. by the director will be transmitted to the first digitreg ster, in the manner explained in detail 1n my first above mentionedcopending application;

' Transmitting the digit.

The sending mechanism having completed v sending the second digit,restores the countingrelays to normal, and restarts the impulsesending,eis in a position to send out the last digit of the call number431, inthis case a 1. The sending of the 1.is identical 5 with thesending of thepreviously explained digits and need not now be.described,

Sender cuto f;

spective makecontacts over the fourth digit control wire 4, which isjumpered to; pin 4 and connected through spring 610 to pin at", throughthe jumper to the stop conductor, thence over the stop conductor,through relay 307 to grounded battery. Relay 307 energizes and atsprings 334: opens the start ground circuit to the impulse sen-dingmechanism, thereby removing ground, which was suppliedt-o the testsender over thesender start conductor, from the sending. mocha-7 nism,definitely preventing the sender from transmitting any more impulsestothe di- Itelay 307 upon energizing locks itself to the grounded senderstart conductor over spring 334- and its make contact, thereby holdingitself in energized .position independent of the grounded spring 571.Re-

lay 307 upon energizing removes the ground from the hold 2conductor,thereby unlockring the energized relays of the digit control group,restoring them all tOr'llOl'lllfll in readiness fortransmitting of thenextnumber by the sender.

The director starts impulse/Lg. The director outgoing loop circuit now'connected to the relay 205 over acircuit ineluding the spring 854 of thedirector mechanism, also includes a parallel circuit includ ingconductor 449 to interrupter spring 813, thence back to conductor450.When the director is in position to transmit the-first digit the shortcircuit of the interrupter springs 813 by the springs 854 is removed andthe springs 813 begin opening the loop circuit of relay 205, causingthat relay to impulse and send out the iirst digit. vAt the end of thefirst digit the springs 856 are closed to stop the impulsing by againshort circuiting the impulsing springs, in the well known manner that isexplained in detail in the first of my above mentionedcopendingapplications. In the test director selector the relay 205 upon fallingback opens the previously traced circuit of relay 206, with out effectat this time owing to the fact that relay 206 has locked itself toground over its circuit from grounded key spring 239 and its breakcontact, through springs 238,. through hold 4 conductor, through spring246 and its make contact, through the winding of relay 206 to groundedbattery. Relay 205 upon falling back also closes a circuit from groundthrough spring 260 and its break contact, through spring 244 and itsbreak contact, through springs 248 to the pulse conductor, throughspring 764 and its break contact, through the Winding of relay 712 togrounded battery, with a parallel branch, through spring 1045 toconductor 775, through spring 763 to the test relay conductor, thencethrough the winding of test relay 207 to grounded battery. Relays 207and7l2 energize over this circuit, the latter spring 752 forming alocking circuit for itself in series with the relay 701, which isconnected to the grounded hold conductor. Relay 701 does not energize atthis time-for thereason that the ground on the pulse conductor shortcircuits the relay. Relay .207 upon energizing at spring 250 closesacircuit'from grounded start conductor through the fault release key261, through spring 254, spring 250 and its make contact to the windingof relay 209. Relay 209 upon energizing locks itself to the faultrelease conductor through spring 253 and spring 258, independent of thespring 250. At the end of the first impulse the relay 205energizes againopening the previously traced circuit to relays 712 and 207. Relay 207being slow to release because of the copper slug on its core, remainsenergized during iinpulsing.

I l Vhen the round is removed from the ulse wire, relay 701, which wasshort circuited by that ground is no longer short circuited andenergizes over a circuit from the grounded holding conductorthroughrelay 701 through springs 52, through the winding of relay 712,to grounded. battery. Relay 701 upon energizing extends the pulse wireto relays 702 and 713, and extends the explained, the second impulseWill lock up,

relays 702 and 713 in a similar manner and the third impulse will lockuprelays 703 and 714. The fault conductor will now be connected throughsprings 730, 731, and '7 32 and their respective make contactsv tosprings 7 33, and the lamp ground will be connected through springs 741,742, and 743 and their respective makev contacts to the springs 744, andthe pulse wire will be connected through springs 764, 765, and 766 andtheir respective make contacts to the springs 767.

Testing the digit received.

' lVhen the spring 856 of the director short circuits the interruptersprings 813, the re lay205 comes to rest energized, opening the circuitoftest relay 207, which restores after a brief interval and closes thetest circuit,

.which may be traced from grounded start conductor through the faultrelease key 261 and thence over the previously traced circuit to thespring 250, which is now resting against its break contact, through thesprings,

255, and thence over two paths in parallel, the one through theWinding-of relays 211 and 210 in series to grounded negative battery,and the other over the fault conductor,

which has been traced to spring 733 now resting against its breakcontact through the third impulse Wire of the receiver IDF, now jumperedto the first digit pin 6, through spring 617 and its make contact to thefirst digit pin '1 through the jumper to digit pin 1, thence over thedigit 1 conductor to springs 822, through spring 822 and its breakcontact to the test conductor, through the receiver IDF through spring616 and itsv make contact to the junction point between relays .210 and211. The impulse having been correctly received, relay2l1 is now shortcircuited, ground being present on both terminals, and that relaytherefore does not energize. Relay 210, energizes over the circuit justtraced including the test conductor and at springs 268 opens the lockingcircuit of relay 209, allowing that relay to restore. Simultaneouslywith the establishment of the just described circuit to relay 210 ,aparallel branch is established from the digit 1 conductor throughsprings 821 to the winding of relay 805 to grounded battery. Relay 805energizes over this circuit and at springs 824 prepares a lockingcircuit foritself in series with relay 801. Relay 801 being shortcircuited at this time by having ground po tential on both terminals isprevented from its make contact to the second digit control wire tospring 827. Relay 209 upon deenergizmg at springs 256 breaks the holdingcircuit for the receiver impulse counting relays 701 to 714, which wereenergized and locked to the hold conductor in counting oifthe firstdigit, thereby restoring the test set to normal in readiness for thereception of the second digit which in this case will be a 4.

A fault on the first digit. In the event that the director had failed tosend out a 3, for the first digit of the call number, when the testrelay 207 energized and the fault and test circuit was established, therelay 211 would not have been short c-ircuited for the reason that thefault wire would not have been connected to the test wire over the loopcircuit previously described. Assume for the moment that the directorhad sent out a 4 for the first digit instead of a 3. The fault wirewould have been connected through springs 733 and its make contact tothe springs 734 and its break contact to the fourth impulse pin on thereceiver IDF, and the lamp ground conductor would have been connected tospring 7 44 and its make contact through the spring 745 and thence tothe digit lamp 4. The fourth receiver IDF impulse pin, being multipledto the second digit control wire I instead of the first, would havecaused the receiving of the digit 4 as a first digit to be registered asa fault, for the reason that the test circuits which were. tracedthrough spring 822 and its break contact to thedigit 1 conductor wouldnot have been connected to the fault wire, since the relay 704 wouldhave been energized by the last impulse of the digit and the contact 733would be made instead of broken. Therefore the relay 211 would not beshort circuited and would energize in series with the relay 210. Therelay 210 being marginal will not energize in se ries with relay 211.Relay 2 11 upon cnergizing, at springs 260 opens the ground circuit tothe impulse springs 244 of the relay 205, thereby preventing theimpulsing relay 205 from having any effect upon the receiving mechanism.The spring 260 clos-- ing a circuit to its make contact closes a circuitfrom ground to the lamp ground conductor which is prO ected throughsprings 741, 742,743, 744, and'745 through the" fourth impulse lamp tobattery. With a.

branch circuit through spring 615 and its make contact, through the lampground conductor 2, through spring 833 and its break contact, throughthe digit lamp 1 to battery. The relay 211 upon energizing furthercloses a circuit from ground through.

resistance 262, through spring 259 and its make contact through theimpulse wire leading to the director-" A circuit is completed I throughthe grounded resistance 262, spring 259 and its make, contact, impulsewire I through relay 702 of the directoiythrough' wiper 719 now inengagement with la'st digit reg1ster, through the magnet of thatregister to grounded battery. The relay 702-energizes over this circuitthereby preventing the d1rector from cuttmg off. The high resistance of262 preventsthe digit register motor H magnet from energizing in serieswith that resistance and relay 702. The director proceeds to impulse theremaining digits .of the call number, but since the ground has re-'moved from the impulsesprings 205,.this

The lampimpulsing is without effect. ground conductor is; further.multipled to the audible signal 412, which sounds to call the attendantsattention to the fault. The

grounded lamp conductor has lighted the fourth impulse lamp, the firstdigit lamp,

and sounded the audible signal calling the attendant to the test set-up,who will investigate the trouble. The attendant will note the directorbeing tested, that being indicated by the director number lamp which islighted from the grounded director selector wiper 222 through theobvious ,circuitto the Inc recordchart, giving the correct number fortest set-up A and will note that the first digit should have containedthree impulses instead of four. The ground placed on the impulseconductor by the fault relay 211, prevents the director from cutting oiland releasing itself from the test set, and furthermore prevents thedirector from restoring to normal so that the attendant will find thedirector set just as it was when it sent out the faulty digit.

The attendant upon.

finding the trouble with the director, will repair the trouble, and ifhe desires to exercise that director, will operate the key springs 241to cut off the director selector motor magnet thereby permitting him toex; ercise the director in a manner which will be explained hereinafter.Having repaired the director, the attendant operates the faultreleasekey 261, removing ground from the re-.

nae

